Figures from one union found as many as 85 per cent of teachers reported the use of CCTV in their schools and one-in-10 said cameras had even been placed in toilets.

The latest study, which features contributions from a series of academics, said: “The use of CCTV has migrated from perimeter security and access control to monitoring pupil behaviour in public areas such as in corridors and playgrounds, and to more private realms such as changing rooms and toilets.”

The report added that some schools failed to understand “their new regulatory responsibilities” as the nature of CCTV usage has changed.

“These issues are only likely to intensify with new uses for cameras in education, such as the remote-operated webcams on laptops provided for pupils’ homes in the USA,” said the study.

“Similar practices are more likely in the UK if private sector management of state schools spreads, as the Government intends.”

The Information Commissioner’s Office – a quango set up to promote data protection and uphold transparency among public bodies – said that complaints over the use of CCTV had risen in recent years.

It said that growing numbers of school staff reported that “CCTV installed to control pupil behaviour has been used to monitor their teaching performance”.

David Smith, deputy information commissioner, told the Times Educational Supplement that cameras should only be used to monitor pupil behaviour in exceptional circumstances.

Constant monitoring of whole classes to crack down on low-level disruption was not justified, he said.